Displacement measuring device

Abstract

A displacement measuring device includes: a probe having a telescopic structure capable of extending and contracting as a whole; and a measuring unit configured to measure a displacement of a front end relative to a base end of the probe, the probe includes a single cylindrical body or a plurality of cylindrical bodies having different diameters and a columnar or cylindrical front end member that is movably inserted into the single cylindrical body or the cylindrical body having the smallest diameter and of which a front end is mounted to a displacement measuring object, and the single or the plurality of cylindrical bodies and the front end member have a rotation applying mechanism that applies a rotation movement in conjunction with a forward/backward movement when the inner cylindrical body or the front end member moves forward/backward relative to the outer cylindrical body in an extension and contraction direction.

The invention claimed is: 
     
       1. A displacement measuring device comprising:
 a probe configured to have a telescopic structure that is capable of extending and contracting as a whole; and 
 a measuring unit configured to measure a displacement of a front end relative to a base end of the probe, 
 the probe including a single cylindrical body or a plurality of cylindrical bodies having diameters different from each other and a columnar or cylindrical front end member that is movably inserted into the single cylindrical body or the cylindrical body having the smallest diameter of the plurality of cylindrical bodies and of which a front end is mounted to a displacement measuring object, and 
 the single or the plurality of cylindrical bodies and the front end member having a rotation applying mechanism that applies a rotation movement in conjunction with a forward/backward movement when an inner cylindrical body of the cylindrical bodies or the front end member moves forward/backward relative to an outer cylindrical body of the cylindrical bodies in an extension and contraction direction, wherein 
 the rotation applying mechanism includes: 
 groove portions that are provided in the outer cylindrical bodies of the cylindrical bodies and are inclined relative to the extension and contraction direction; and 
 guide pins that are provided on outer peripheries of the inner cylindrical bodies of the cylindrical bodies or the front end member and are loosely fitted into the groove portions. 
 
     
     
       2. The displacement measuring device according to  claim 1 , wherein
 the measuring unit includes: 
 a displacement detecting unit including a rotation displacement meter that is provided in the probe and detects a rotation angle of the cylindrical body having the largest diameter relative to the front end member; and 
 a calculation unit that calculates a displacement of the displacement measuring object based on an output value from the displacement detecting unit. 
 
     
     
       3. The displacement measuring device according to  claim 2 , wherein
 the measuring unit includes an inclination angle detection unit including a plurality of rotation displacement meters that detects rotation angles around axes perpendicular to an axis of the probe and perpendicular to each other as an inclination angle of the entire device. 
 
     
     
       4. The displacement measuring device according to  claim 1 , wherein
 the measuring unit includes: 
 a displacement detecting unit including a variable resistor that is provided in the probe and detects displacements of the cylindrical body having the largest diameter and the cylindrical body disposed on the inner side of the cylindrical body having the largest diameter in the extension and contraction direction; and 
 a calculation unit that calculates a displacement of the displacement measuring object based on an output value from the displacement detecting unit. 
 
     
     
       5. The displacement measuring device according to  claim 4 , wherein
 the measuring unit includes an inclination angle detection unit including a plurality of rotation displacement meters that detects rotation angles around axes perpendicular to an axis of the probe and perpendicular to each other as an inclination angle of the entire device. 
 
     
     
       6. The displacement measuring device according to  claim 1 , wherein
 the guide pins are disposed at equal intervals along a circumferential direction of the cylindrical bodies and the front end member, and the guide pins provided on the adjacent cylindrical bodies or the cylindrical body and the front end member adjacent to each other are disposed to be shifted from each other in the circumferential direction as viewed from the extension and contraction direction. 
 
     
     
       7. The displacement measuring device according to  claim 6 , wherein
 the measuring unit includes an inclination angle detection unit including a plurality of rotation displacement meters that detects rotation angles around axes perpendicular to an axis of the probe and perpendicular to each other as an inclination angle of the entire device. 
 
     
     
       8. The displacement measuring device according to  claim 1 , wherein
 the measuring unit includes an inclination angle detection unit including a plurality of rotation displacement meters that detects rotation angles around axes perpendicular to an axis of the probe and perpendicular to each other as an inclination angle of the entire device.